2008+ S40/C30 Airbag Resistance

janoush · Post by **janoush** » 09 Feb 2010, 10:18

Does anybody know the resistance of a good airbag? I'm trying to bypass the collapsable steering column release charge but do not know its resistance, I'm willing to bet it's the same as an airbag. I've tried 2.5ohms and 3.3ohms without any luck. The SRS module has been reset and the dealer said as long as the battery is unplugged during reinstalling the column the light will go off during the SRS cycle test.

Volvo does not sell the release charge separately, only the $800 column. It is crazy that they force you to replace the column even if it hasn't moved (you can see the alignment mark on the last photo). The release charge drops a pin that allows the column to slide towards the firewall in an accident. There is a glue used to keep the column from sliding during normal use, mine didn't even move from an accident that deployed the airbag!

Here are a few photos illustrating what I'm talking about:

janoush · Post by **janoush** » 10 Feb 2010, 12:06

A 2.0ohm resistor worked, I just had the codes cleared at Volvo, no lights!

For anybody searching... 2008+ volvo s40 / volvo c30 airbag resistance / seatbelt resistance / collapsable steering column resistance are 2.0 ohms. I used 5x 10 ohm 1/4 watt resistors from Radioshack ($.99) and soldered them in parallel.

Post by **vegasjetskier** » 10 Feb 2010, 12:12

So now your steering column won't collapse in an accident? Doesn't that concern you?

janoush · Post by **janoush** » 10 Feb 2010, 12:22

vegasjetskier wrote:So now your steering column won't collapse in an accident? Doesn't that concern you?

It will collapse in an accident. There's a pin that moves down to allow the column to slide during an impact. I left it in the down position. There is also glue to keep the column from sliding inadvertently during normal use. I'm guessing the pin is an extra precaution incase someone hits the wheel really hard while getting into the car or something of that nature.

My column did not move (with the pin down) from this accident, including an airbag deployment:

Even with the pin down, it takes a serious hit to move the column.

Dano · Post by **Dano** » 18 Feb 2011, 11:48

Cant you just replace the column lock that drops the pin down?

Post by **jimmy57** » 18 Feb 2011, 12:25

The pin is blown out to allow lowered force for yield if belt is worn. Belt has controlled force yield.
If no belt is worn then you do not have the belt protection and the column has a higher yield force to act as force absorption.

How much were the belts?

The column can be injured with no visible evidence and not be as effective and selling the charge would condone re-using the column.

Dano · Post by **Dano** » 05 Mar 2011, 17:22

How do I wire the 2.0ohm resistor into place, as in what wires do I use and how do I wire it in parallel? Do I use one 5x 10 ohm 1/4 watt resistor or two? I have a 2007 C70 with the same issue and hope it will fix it.

janoush · Post by **janoush** » 18 Mar 2011, 14:25

You can remove the harness from the steering column, then make a U with a resistor and slide each leg into the two sockets in the harness clip. I purchased 1/2 watt 2ohm resistors, using multiple resistors was not accurate enough for the SRS system. I've had 6k miles on mine without an SRS light on.

You might consider looking for a used column, I've seen some for around $80 shipped (Make sure the airbag didn't go off in the donor car!) If you ever sell the car you don't want a resistor in the SRS system...